I'm going to disagree here, your friend gave you a really good deal on the plow knowing you wanted a plow for yourself, selling it for a profit will cause hard feeling, just use the plow.

...or trade/sell it to a wh collector for a used plow + extras, then give the extras to your friend as thanks, that's 3 people winning in one deal. of course i don't know anyone involved just my take on it from my lounge chair...